Method and composition for enhancing the insecticidal activity of certain organophosphorus compounds

ABSTRACT

The insecticidal activity of certain pyridinyl phosphorus compounds is enhanced by the admixture therewith of certain 2,4-disubstituted-5-pyrimidinyl phosphoramidothioates.

Cross-Reference to Related Application

This is a continuation, of application Ser. No. 125,909, filed November 27, 1987 now abandoned which in turn is a continuation of Ser. No. 489,422, filed Apr. 28, 1983, now abandoned.

BACKGROUND OF THE INVENTION

Organophosphorus compounds are as a group one of the most widely-used insecticides in agriculture. The pyridinyl phosphorus insecticides are a highly active group of compounds used for the kill and control of a great variety of insects.

It has been found, however, that certain pyridinyl phosphorus insecticides are not highly effective in the kill and control of insects of the order Lepidoptera and especially of the genus Heliothis. The reasons for the ineffectiveness of these pyridyl phosphorus insecticides are not fully known nor understood. It is believed that by some mechanism, insects from the above group are insensitive to these phosphorus compounds. Since these insects are of economic importance, methods are continually being sought to increase the activity of these insecticides in the control of insects of the order Lepidoptera.

SUMMARY OF THE INVENTION

The present invention is directed to a method of and compositions for enhancing the insecticidal activity of certain pyridinyl phosphorus insecticides which comprises admixing with the pyridinyl phosphorus insecticide, and activity enhancing amount of a 2,4-disubstituted-5-pyrimidinyl phosphoramidothioate.

As indicated hereinabove, certain pyridinyl phosphorus insecticides have been found to be ineffective in the kill and control of insects of the order Lepidoptera and especially of the genus Heliothis. This ineffectiveness is not fully known or understood. It has been suggested that by some mechanism, insects from the above group have the ability to detoxify or otherwise inhibit the insecticidal activity of the phosphorus compounds.

In order to overcome or bypass this ineffectiveness, prior methods have involved the use of larger treating or dosage amounts of the insecticide or the use of an additional insecticide which is active against insects of the order Lepidoptera. Neither the use of larger dosages nor the use of an additional insecticide has proven to be satisfactory.

The present invention is conducted by contacting insects of the order Lepidoptera and especially the genus Heliothis or their habitat with a composition containing one part of the insecticidally active pyridinyl phosphorus compound to be enhanced and from about 1/16 part to about 16 parts of the 2,4-disubstituted-5-pyrimidinyl phosphoramidothioate, i.e., a ratio of about 16:1 to about 1:16. A preferred ratio is from about 8:1 to about 1:1 with the most preferred ratio being from about 8:1 to about 2:1.

The exact mechanism by which the pyrimidinyl phosphoramidothioates are able to enhance the activity of the pyridinyl phosphorus compounds is not fully understood. One theory, for which the applicants do not wish to be bound, suggests that insects of the order Lepidoptera and especially of the genus Heliothis possess an acetylcholinesterase enzyme which is partially insensitive to the pyridinyl phosphorus compounds. The pyrimidinyl phosphoramidothioates are thought to modify the acetylcholinesterase enzyme such that its sensitivity to pyridinyl phosphorus compounds is increased.

The pyrimidinyl phosphoramidothioates are themselves poor insecticides but when employed with the pyridinyl phosphorus compounds, appear to make insects of the order Lepidoptera susceptible to the insecticidal action of the pyridinyl phosphorus compounds.

The pyridinyl phosphorus insecticides found to be enhanced by the pyrimidinyl phosphoramidothioates are those which correspond to the formula ##STR1## wherein each X independently represents bromo, chloro, fluoro or iodo; Z represents oxygen or sulfur; each R independently represents alkoxy of 1 to 4 carbon atoms and n represents an integer of from 1 to 3.

The preferred pyridinyl phosphorus insecticides are those compounds wherein X is chloro or fluoro and Z is sulfur. The most preferred insecticides are those compounds wherein X is chloro, n is 3, Z is sulfur and R is methoxy or ethoxy. These compounds, their methods of preparation and their insecticidal uses are taught in U.S. Pat. No. 3,244,586.

The pyrimidinyl phosphoramidothioates which are employed as activity enhancers are derivatives of 5-pyrimidinols and correspond to the formula ##STR2## wherein A represents alkyl of 1 to 4 carbon atoms, cycloalkyl of 3 or 4 carbon atoms, alkyl(cycloalkyl) wherein the alkyl group is of 1 to 4 carbon atoms and the cycloalkyl group is of 3 or 4 atoms, (cycloalkyl)alkyl wherein the alkyl group is of 1 to 4 carbon atoms and the cycloalkyl group is of 3 or 4 carbon atoms, dialkylamino wherein each alkyl group is independently of 1 to 4 carbon atoms or morpholino; D represents hydrogen, methyl, alkoxy of 1 to 4 carbon atoms or alkylthio of 1 to 4 carbon atoms; R¹ represents alkyl of 1 to 4 carbon atoms; R² represents monoalkylamino of 1 to 4 carbon atoms, dialkylamino wherein each alkyl group is independently of 1 to 4 carbon atoms or monocycloalkylamino of 3 to 4 carbon atoms and Z is oxygen or sulfur.

The preferred pyrimidinyl phosphoramidothioates are those wherein Z is sulfur; R¹ represents alkyl of 1 to 3 carbon atoms; R² represents monoalkylamino or cyclopropylamino; A represents alkyl, cyclopropyl, 1-methylcyclopropyl or cyclopropylmethyl and D is hydrogen.

A most preferred group of the pyrimidinyl phosphoramidothioates include those compounds wherein Z is sulfur; R¹ is ethyl; R² represents monoalkylamino or cyclopropylamino; A represents isopropyl, tertiary butyl, cyclopropyl or 1-methylcyclopropyl and D is hydrogen.

In the present specification and claims, the terms "alkyl", 37 alkoxy ", "alkylthio", "dialkylamino" and "monoalkylamino" are employed to designate alkyl, alkoxy, alkylthio, monoalkylamino and dialkylamino radicals wherein the alkyl portion can be either straight or branched chained.

The pyrimidinyl compounds are for the most part known and are taught in U.S. Pat. Nos. 4,127,652 and 4,325,948 and European patent application 23841 (CA. 95:25114q).

Those pyrimidinyl compounds which correspond to one of the formulae ##STR3## wherein A,D,Z,R¹ and R² are as hereinabove defined and R³ is cycloalkyl of 3 or 4 carbon atoms are also novel compounds and constitute a part of the present invention. While these compounds and their preparation are not taught by the above set-forth references, they can be prepared employing procedures analogous to those taught in said references employing the appropriate starting materials.

In a representative procedure for preparing all of the pyrimidinyl compounds, substantially equimolar amounts of an appropriate pyrimidinol reactant corresponding to the formula ##STR4## and an appropriate chlorophosphorus reactant corresponding to the formula ##STR5## are reacted together in the presence of a solvent and a HCl absorber (acid-binding agent) at a temperature in the range of from about 10° C. to about 100° C. This preparative procedure can be represented by the following reaction scheme ##STR6## wherein A, D, R¹, R² and Z are as hereinbefore defined. No attempt has been made to present a balanced equation.

Representative solvents include those taught in the above references with a preferred solvent being acetonitrile. Representative HCl absorbers include those taught in the above references with a preferred absorber being potassium carbonate. After the completion of the reaction, the insoluble salts are removed by filtration and the filtrate concentrated by evaporation under reduced pressure. The product which remains as a residue is purified by taking up the residue in a solvent such as ether and washing the mixture with a dilute alkaline material such as dilute sodium hydroxide and then with a saturated brine solution such as saturated sodium chloride. The mixture is dried and the solvent removed leaving the desired product.

Preparation of Starting Materials

The N-cyclopropyl O-alkyl phosphoramidochloro compounds corresponding to the formula ##STR7## can be prepared by reacting an alkyl phosphorodichloridothioate or alkyl phosphorodichloridate with a substantially two molar amount of cycloproplyamine in the presence of an inert solvent.

In carrying out this reaction cyclopropylamine is added slowly to a stirred solution of an alkyl phosphorodichloridothioate or an alkyl phosphorodichloridate. The reaction is carried out at a temperature of approximately 0° C. The reaction is complete when all of the phosphorus reactant has been consumed.

Representative solvents include, for example, methylene chloride, ether, benzene, toluene and the like.

At the completion of the reaction, the reaction mixture is filtered to remove precipitated cyclopropylamine hydrochloride and the filtrate is concentrated under reduced pressure. The residue can be used directly or be purified by distillation under vacuum.

The 2-morpholino-4-substituted-5-pyrimidinols corresponding to the formula ##STR8## wherein D is hydrogen can be prepared by the reaction between 4-morpholinecarboximidamide sulfate and N-(3-(dimethylamino)-2-ethoxy-2-propenylidene)-N-methylmethanaminium perchlorate (Z. Arnold, Collect. Czech. Chem. Commun. 38, 1168-72 (1973)) in the presence of sodium methoxide and using methanol as solvent to give 5-ethoxy-2-morpholinopyrimidine. The ethoxy group is then converted to the OH group using sodium ethylmercaptide in dimethylformamide.

The 4-methyl-2-morpholino-5-pyrimidinol (D represents methyl) can be prepared by reacting methyl methoxyacetate with sodium hydride in toluene and the product is then reacted with 4-morpholinecarboximidamide sulfate to give 5-methoxy-6-methoxymethyl-2-morpholino-4-pyrimidinol. This latter compound is converted to 4-chloro-5-methoxy-6-methoxymethyl-2-morpholinopyrimidine by reaction with phosphorus oxychloride. The ring chlorine and the methoxy group in the methoxymethyl group are replaced with hydrogen on reduction with zinc in 1 normal NaOH and reaction with sodium ethylmercaptide in dimethylformamide then yields the desired pyrimidinol.

The 4-alkylthio-2-morpholino-5-pyrimidinols (D represents alkylthio) can be prepared by reacting a 1:1 mixture of methyl methoxyacetate and ethyl formate with sodium hydride in toluene and the product is then reacted with 4-morpholinecarboximidamide sulfate to give 5-methoxy-3-morpholino-4-pyrimidinol. The latter compound is converted to 4-chloro-5-methoxy-2-morpholinopyrimidine by reaction with phosphorus oxychloride. The ring chlorine is then replaced by an alkylthio group by the reaction with an alkali alkylmercaptide to give 4-alkylthio-5-methoxy-2-morpholinopyrimidine. The methoxy group is then converted to a OH group using sodium ethyl mercaptide in dimethylformamide.

The 4-alkoxy-2-morpholino-5-pyrimidinols (D represents alkoxy) can be prepared by reacting a 1:1 mixture of ethyl benzyloxyacetate and ethyl formate with sodium hydride in toluene and the product is then reacted with 4-morpholinecarboximidamide sulfate to give 5-benzyloxy-2-morpholino-4-pyrimidinol. The latter compound is converted to 5-benzyloxy-4-chloro-2-morpholinopyrimidine by reaction with phosphorus oxychloride. The ring chlorine is then replaced by an alkoxy group with an alkali alkoxide to give 4-alkoxy-5-benzyloxy-2-morpholinopyrimidine. The benzyloxy group is then converted to the OH group by hydrogenation in the presence of a solvent and a hydrogenation catalyst.

Description of Some of the Preferred Embodiments

The following examples illustrate the present invention and the manner by which it can be practiced but, as such, should not be construed as limitations upon the overall scope of the same.

EXAMPLE I N-Cyclopropyl O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl phosphoramidothioate ##STR9##

A mixture of 3.0 grams (g) of 2-cyclopropyl-5-pyrimidinol, 3.0 g of finely-powdered potassium carbonate, 50 ml of acetonitrile and 4.1 g of N-cyclopropyl O-ethyl phosphoramidochloridothioate was stirred, without external heating, until all of the phosphorus starting reactant had been consumed as shown by gas-liquid chromatography (GLC). The insoluble salts were removed by filtration and the filtrate concentrated by evaporation under vacuum. The residue was dissolved in ether, and the ether solution was washed twice with 2 percent aqueous sodium hydroxide, once with a saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was removed in a rotary evaporator leaving 4.9 g (74 percent of theoretical) of the above-identified product as a pale amber colored oil. The product had a refractive index of n25/D=1.5325. Upon analysis, the product was found to have carbon, hydrogen and nitrogen contents of 47.97, 6.04 and 13.94 percent, respectively, as compared with the theoretical contents of 48.15, 6.06 and 14.04 percent, respectively, as calculated for the above-named compound.

EXAMPLE II N-Cyclopropyl O-(2-(4-morpholino)-5-pyrimidinyl) O-ethyl phosphoramidothioate ##STR10##

A mixture of 3.44 g of 2-(4-morpholino)-5-pyrimidinol, 3.2 g of finely-powdered potassium carbonate, 25 ml of acetonitrile and 3.59 g of N-cyclopropyl O-ethyl phosphoramidochloridothioate was stirred, without external heating, until all of the phosphorus starting reactant had been consumed as shown by gas-liquid chromatography (GLC). The insoluble salts were removed by filtration and the filtrate concentrated by evaporation under vacuum. The residue was dissolved in ether, and the ether solution was washed twice with 2 percent aqueous sodium hydroxide, once with saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was removed in a rotary evaporator leaving 3.3 g (53 percent of theoretical) of the above-identified product as an amber colored oil. The product had a refractive index of n25/D=1.5604. Upon analysis, the product was found to have carbon, hydrogen and nitrogen contents of 46.61, 6.11 and 16.27, respectively, as compared with the theoretical contents of 45.34, 6.15 and 16.27 percent, respectively, as calculated for the above named-compound.

EXAMPLE III N-Cyclopropyl O-(2-cyclopropyl-4-methyl-5-pyrimidinyl) O-ethyl phosphoramidothioate ##STR11##

A mixture of 2.5 g of 2-cyclopropyl-4-methyl-5-pyrimidinol, 4.0 g of finely-powdered potassium carbonate, 50 ml of acetonitrile and 4.0 g of N-cyclopropyl O-ethyl phosphoramidochloridothioate was stirred, without external heating, until all of the phosphorus starting reactant had been consumed as shown by gas-liquid chromatography (GLC). The insoluble salts were removed by filtration and filtrate concentrated by evaporation under vacuum. The residue was dissolved in ether, and the ether solution was washed twice with 2 percent aqueous sodium hydroxide, once with saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was removed in a rotary evaporator leaving 2.5 g (44 percent of theoretical) of the above-identified product as an amber colored oil. The product had a refractive index of n25/D=1.4621. Upon analysis, the product was found to have carbon, hydrogen and nitrogen contents of 49.43, 6.46 and 13.56, respectively, as compared with the theoretical contents of 49.82, 6.43 and 13.41 percent, respectively, as calculated for the above-named compound.

EXAMPLE IV O-(2-(4-Morpholino)-5-pyrimidinyl) O-ethyl N-(1-methylethyl) phosphoramidothioate ##STR12##

A mixture of 3.44 g of 2-(4-morpholino)-5-pyrimidinol, 3.2 g of finely-powdered potassium carbonate, 25 ml of acetonitrile and 3.63 g of N-(1-methylethyl) O-ethyl phosphoramidochloridothioate was stirred without external heating, until all of the phosphorus starting reactant had been consumed as shown by gas-liquid chromatography (GLC). The insoluble salts were removed by filtration and the filtrate concentrated by evaporation under vacuum. The residue was dissolved in ether, and the ether solution was washed twice with 2 percent aqueous sodium hydroxide, once with saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was removed in a rotary evaporator leaving 4.5 g (72 percent of theoretical) of the above-identified product as an amber colored oil. The product had a refractive index of n25/D=1.5534. Upon analysis, the product was found to have carbon, hydrogen and nitrogen contents of 46.28, 6.52 and 16.92, respectively, as compared with the theoretical contents of 45.08, 6.69 and 16.18 percent, respectively, as calculated for the above-named compound.

The insecticidal compositions of the present invention are especially effective in killing and controlling insects, particularly Lepidoptera, and especially Heliothis species, which infest crops such as corn, soybeans, tobacco and particularly cotton.

Representative insects of the order Lepidoptera which can be killed and controlled by the practice of the present invention include, for example, but are not limited to, members of the order of Lepidoptera such as the beet armyworm (Spodoptera exigua), the Egyptian cotton leafworm (Spodoptera littoralis), the black cutworm (Agrotis ipsilon), the pink bollworm (Pectinophora gossypiella), the codling moth (Laspeyresia pomonella) and especially members of the genus Heliothis including the tobacco budworm (Heliothis virescens), the corn earworm (Heliothis zea) and the American bollworm (Heliothis armigera).

Other insects controlled by the practice of the present invention, include, but are not limited to, members of the order Acarina, such as the two-spotted spider mite (Tetranychus urticae); members of the order Hemiptera, such as the lygus bug (Lygus hesperus); members of the order Coleoptera, such as the cotton boll weevil (Anthonomus grandis), the alfalfa weevil (Hypera postica), and the Western spotted cucumber beetle (Diabrotica undecipunctata undecipunctata); members of the order Diptera, such as the housefly (Musca domestica); members of the order Orthoptera, such as the German cockroach (Blattella germanica); members of the order Homoptera, such as the aster leafhopper (Macrosteles fascifrons) and the cotton aphid (Aphis gossyppii).

The mixture of active compounds, i.e., active mixture of the present invention have been found to possess good activity against Heliothis species. Accordingly, the present invention also comprises methods for controlling such insects by applying to said insects and/or their habitats a pesticidally effective amount of the active mixture of compounds. For such uses the unmodified active materials of the present invention can be employed. However, the present invention embraces the use of an insecticidally-effective amount of the active materials in admixture with an inert material, as an adjuvant or carrier therefor, in solid or liquid form. Thus, for example, the active mixture can be dispersed on a finely-divided solid and employed therein as a dust. Also, the active mixture, as liquid concentrates or solid compositions comprising the active mixture, can be dispersed in water, typically with the aid of a wetting agent, and the resulting aqueous dispersion employed as a spray. In other procedures, the active mixture can be employed as a constituent of organic liquid compositions, oil-in-water and water-in-oil emulsions, or water dispersions, with or without the addition of wetting, dispersing or emulsifying agents.

Suitable adjuvants of the foregoing type are well known to those skilled in the art. The methods of applying the solid or liquid pesticidal formulations similarly are well known to the skilled artisan.

As liquid carriers or adjuvants, organic solvents can be employed hydrocarbons, e.g., toluene, xylene, kerosene, diesel fuel, fuel oil, and petroleum naphtha, ketones such as acetone, methyl ethyl ketone and cyclohexanone, chlorinated hydrocarbons such as chloroform, trichloroethylene, and perchloroethylene, esters such as ethyl acetate, amyl acetate and butyl acetate, ethers, e.g., ethylene glycol monomethyl ether and diethylene glycol monomethyl ether, alcohols, e.g., methanol, ethanol, isopropanol, amyl alcohol, ethylene glycol, propylene glycol, butyl carbitol acetate and glycerine. Mixtures of water and organic solvents, either as solutions or emulsions, can be employed.

The active mixtures can also be applied as aerosols, e.g., by dispersing them in air by means of a compressed gas such as dichlorodifluoromethane or trichlorofluoromethane and other such materials.

The active mixture of the present invention can also be applied with solid adjuvants or carriers such as talc, pyrophyllite, synthetic fine silica, attapulgus clay, kieselguhr, chalk, diatomaceous earth, lime, calcium carbonate, bentonite, fuller's earth, cottonseed hulls, wheat flour, soybean flour, pumice, tripoli, wood flour, walnut shell flour, redwood flour and lignin.

As stated, it is frequently desirable to incorportate a surface active agent in the compositions of the present invention. Such surface active or wetting agents are advantageously employed in both the solid and liquid compositions. The surface active agent can be anionic, cationic or nonionic in character.

Typical classes of surface active agents include alkyl sulfonate salts, alkylaryl sulfonate salts, alkylaryl polyether alcohols, fatty acid esters of polyhydric alcohols and the alkylene oxide addition products of such esters, and addition products of long chain mercaptans and alkylene oxides. Typical examples of such surface active agents include the sodium alkylbenzene sulfonates having 10 to 18 carbon atoms in the alkyl groups, alkylphenol ethylene oxide condensation products, e.g., p-isooctylphenol condensed with 10 ethylene oxide units, soaps, e.g., sodium stearate and potassium oleate, sodium salt of propylnaphthalene sulfonic acid, di-(2-ethylhexyl)-ester of sodium sulfosuccinic acid, sodium lauryl sulfate, sodium decyl sulfonate, sodium salt of the sulfonated monoglyceride of coconut fatty acids, sorbitan sesquioleate, lauryl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, polyethylene glycol lauryl ether, polyethylene glycol esters of fatty acids and rosin acids, e.g., Ethofat 7 and 13, sodium N-methyl-N-oleyl taurate, Turkey Red Oil, sodium dibutyl napthalene sulfonate, sodium lignin sulfonate, polyethylene glycol stearate, sodium dodecylbenzene sulfonate, tertiary dodecyl polyethylene glycol thioether (nonionic 218), long chain ethylene oxide-propylene oxide condensation products, e.g., Pluronic 61 (molecular weight 1000), polyethylene glycol ester of tall oil acids, sodium octyl phenoxyethoxyethyl sulfate, tris-(polyoxyethylene)-sorbitan monostearate (Tween 60), and sodium dihexyl sulfosuccinate. The active mixture of the present invention can be applied in a formulation which contain about an equal volumetric amount, based on the volume of the active mixture present in said formulation, of (a) a polypropylene glycol having an average molecular weight from about 1,000 to about 5,000; (b) a water insoluble polybutylene glycol; and (c) mixtures and copolymers of (a) and (b). The polypropylene glycols, polybutylene glycols, their mixtures, and co-polymers are all known.

The concentration of the active mixtures in liquid formulations generally is from about 0.01 to about 95 percent by weight or more. Concentrations of from about 0.1 to about 50 weight percent are often employed. In formulations to be employed as concentrates, the active materials can be present in a concentration of from about 5 to about 98 weight percent. In dusts or dry formulations, the concentration of the active ingredient can be from about 0.01 to about 95 weight percent or more; concentrations of from about 0.1 to about 50 weight percent are often conveniently employed. The active compositions can also contain other compatible additaments, for example, plant growth regulants such as herbicides or growth stimulants, pesticides such as insecticides or fungicides and the like.

The present compositions can be applied by the use of power-dusters, boom and hand sprayers, spray-dusters and by other conventional means. The compositions can also be applied from aircraft as a dust or a spray.

The active mixtures of this invention are usually applied at a rate in the range of from about 1/16 pound to about 5 pounds or more per acre, but lower or higher rates may be appropriate in some cases. A preferred application rate is from 1/4 pound to about 2 pounds per acre.

EXAMPLE V

A study was conducted to determine the base-line amount in parts of the compound per million parts of the ultimate composition (ppm) of each of the hereinafter set-forth pyrimidinyl phosphorus compounds necessary to give at least 95 percent (LD₉₅) kill and control of Heliothis larvae.

Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant.

The leaves of 5-6 week old cotton seedlings were dipped into one of the above mixtures and allowed to dry. When dry they were removed from the plant and placed into Petri dishes. Five (5) late second instar (approximately 5 day old) tobacco budworm larvae (Heliothis virescens) were placed in each dish and the dishes were covered. All treatments were run in triplicate. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants.

The results of this study are set forth below in Table I.

                                      TABLE I                                      __________________________________________________________________________      ##STR13##                                                                     Compound                                                                       Number                                                                               A     D    R.sup.1                                                                             R.sup.2  Z LD.sub.95 in ppm                              __________________________________________________________________________     1     CP    H    Me   NHMe     S >200                                          2     CP    H    Et   NHMe     S >200                                          3     CP    H    Et   NHEt     S >200                                          4     CP    H    Et   NH .sub.-i-P                                                                            S >200                                          5     CP    H    Et   NH -n-P  S >200                                          6     CP    H    Et   NH .sub.-t-B                                                                            S >200                                          7     CP    H    Et   NH .sub.-i-B                                                                            S >200                                          8     CP    H    Et   NH sec-B S >200                                          9     CP    H    Et   NH  -n-B S >200                                          10    CP    H    Et   NHCP     S >200                                          11    CP    H    Et   N(Me).sub.2                                                                             S >200                                          12    CP    H     .sub.-i-P                                                                          NHEt     S >200                                          13    CP    H     .sub.-i-P                                                                          NH sec-B S >200                                          14    CP    H    sec-B                                                                               NH .sub.-i-P                                                                            S >200                                          15    CP    H    Et   NH .sub.-i-P                                                                            O >200                                          16    CP    H    Et   NH sec-B O >200                                          17    CP    H    Et   NH .sub.-i-P                                                                            S >200                                          18    CP    Me   Me   NH .sub.-i-P                                                                            S >200                                          19    CP    Me   Me   NH sec-B S >200                                          20    CP    Me   Et   NHEt     S >200                                          21    CP    Me   Et    NH .sub.-i-P                                                                           S >200                                          22    CP    Me   Et   NH sec-B S >200                                          23    CP    Me   Et   NH .sub.-i-B                                                                            S >200                                          24    CP    Me   Et   NH -n-B  S >200                                          25    CP    Me   Et   NHCP     S >200                                          26    CP    Me   Et   N( .sub.-i-P).sub.2                                                                     S >200                                          27    CP    Me    .sub.-i-P                                                                          NHEt     S >200                                          28    CP    Me   Et   NH .sub.-i-P                                                                            O >200                                          29    CP    OEt  Et   NH .sub.-i-P                                                                            S >200                                          30    CP    SEt  Et   NH .sub.-i-P                                                                            S >200                                          31    1-MeCP                                                                               H    Et   NH .sub.-i-P                                                                            S >200                                          32    CPMe  H    Et   NH .sub.-i-P                                                                            S >200                                          33    CB    H    Et   NH .sub.-i-P                                                                            S >200                                          34     .sub.-i-P                                                                           H    Et   NH .sub.-i-P                                                                            S >200                                          35     .sub.-t-B                                                                           H    Et   NH .sub.-i-P                                                                            S >200                                          36     .sub.-t-B                                                                           Me   Et   NH .sub.-i-P                                                                            S >200                                          37    N(Me).sub.2                                                                          H    Et   NH .sub.-i-P                                                                            S >200                                          38    Mor   H    Et   NH .sub.-i-P                                                                            S >200                                          39    Mor   H    Et   NHCP     S >200                                          __________________________________________________________________________      CP = cyclopropyl                                                               Mor = morpholino                                                                NH sec-B = secondary butylamino                                               1MeCP = 1methylcyclopropyl                                                     OEt = ethoxy                                                                   NH-n-B = -nbutylamino                                                          CPMe = cyclopropylmethyl                                                       SEt = ethylthio                                                                NHCP = cyclopropylamino                                                        CB = cyclobutyl                                                                NHMe = methylamino                                                              N(Me).sub.2 = dimethylamino                                                   Me = methyl                                                                    NHEt = ethylamino                                                              N(.sub.-i-P).sub.2 = diisopropylamino                                          Et = ethyl                                                                     NH.sub.-i-P = isopropylamino                                                   .sub.-i-P = isopropyl                                                          NH-n-P = -npropylamino                                                          sec-B = secondary butyl                                                       NH.sub.-tB = tert. butylamino                                                  .sub.-t-B = tertiary butyl                                                     NH.sub.-i-B = isobutylamino                                              

EXAMPLE VI

A study was conducted to determine the effectiveness and enhancing response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate and O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-(1-methylethyl) phosphoramidothioate (Compound 4) in the control of Heliothis larvae.

Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant.

The leaves of 5-6 week old cotton seedlings were dipped into one of the above mixtures and allowed to dry. When dry they were removed from the plant and placed into Petri dishes. Five late second instar (approximately 5-day old) tobacco budworm larvae (Heliothis virescens) were placed in each dish and the dishes covered. All treatments were run in triplicate. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants.

The results of this study are set forth below in Table II.

                                      TABLE II                                     __________________________________________________________________________                                    Expected                                                                              Actual                                   Test      Amount     Amount                                                                              Ratio of                                                                            Control                                                                               Control                                                                              Percent Increase Over              No..sup.(1)                                                                        Chemical.sup.(2)                                                                     in PPM                                                                              Chemical.sup.(3)                                                                     in PPM                                                                              A to B                                                                              in Percent.sup.(4)                                                                    in Percent                                                                           Expected Control.sup.(5)           __________________________________________________________________________     1   --    --   --    --   --   --     0     --                                 2   A     25   --    --   --   --     22    --                                 3   A     50   --    --   --   --     14    --                                 4   A     100  --    --   --   --     28    --                                 5   A     200  --    --   --   --     71    --                                 6   --    --   B     25   --   --     0     --                                 7   --    --   B     50   --   --     35    --                                 8   --    --   B     100  --   --     49    --                                 9   --    --   B     200  --   --     86    --                                 10  A     25   B     25   1:1  22     22    0                                  11  A     25   B     50   1:2  49     14    -71                                12  A     25   B     100  1:4  60     35    -42                                13  A     25   B     200  1:8  89     92    3                                  14  A     50   B     25   2:1  14     49    50                                 15  A     50   B     50   1:1  44     57    29                                 16  A     50   B     100  1:2  56     64    14                                 17  A     50   B     200  1:4  88     100   14                                 18  A     100  B     25   4:1  28     86    207                                19  A     100  B     50   2:1  53     71    34                                 20  A     100  B     100  1:1  63     100   59                                 21  A     100  B     200  1:2  90     100   11                                 22  A     200  B     25   8:1  71     35    -51                                23  A     200  B     50   4:1  81     86    6.2                                24  A     200  B     100  2:1  85     100   18                                 25  A     200  B     200  1:1  96     100   4                                  __________________________________________________________________________      .sup.(1) Test Nos. 1-9 are control runs with Test 1 being a no chemical        control (surfactant/acetone/water alone).                                      .sup.(2) Chemical A represents O,O--diethyl                                    O--(3,5,6trichloro-2-pyridinyl) phosphorothioate.                              .sup.(3) Chemical B represents O--(2cyclopropyl-5-pyrimidinyl) O--ethyl        N--(1methylethyl) phosphoramidothioate.                                        .sup.(4) Expected control equals % control by chemical A + % control by        chemical B minus (-)                                                           ##STR14##                                                                      ##STR15##                                                                

EXAMPLE VII

A study was conducted to determine the effectiveness and enhancing response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate and N-cyclopropyl O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl phosphoramidothioate (Compound 10) in the control of Heliothis larvae.

Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant.

The leaves of 5-6 week old cotton seedlings were dipped into one of the above mixtures and allowed to dry. When dry they were removed from the plant and placed into Petri Dishes. Five late second instar (approximately 5-day old) tobacco budworm larvae (Heliothis virescens) were placed in each dish and the dishes covered. All treatments were run in triplicate. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants.

The results of this study are set forth below in Table III.

                                      TABLE III                                    __________________________________________________________________________                                    Expected                                                                              Actual                                   Test      Amount     Amount                                                                              Ratio of                                                                            Control                                                                               Control                                                                              Percent Increase Over              No..sup.(1)                                                                        Chemical.sup.(2)                                                                     in PPM                                                                              Chemical.sup.(3)                                                                     in PPM                                                                              A to B                                                                              in Percent.sup.(4)                                                                    in Percent                                                                           Expected Control.sup.(5)           __________________________________________________________________________     1   --    --   --    --   --   --     0     --                                 2   A     50   --    --   --   --     9     --                                 3   A     100  --    --   --   --     75    --                                 4   A     200  --    --   --   --     84    --                                 5   A     400  --    --   --   --     100   --                                 6   --    --   B     50   --   --     0     --                                 7   --    --   B     100  --   --     16    --                                 8   --    --   B     200  --   --     50    --                                 9   --    --   B     400  --   --     100   --                                 10  A     50   B     50   1:1  9      66    7                                  11  A     50   B     100  1:2  24     100   316                                12  A     50   B     200  1:4  54     91    68                                 13  A     50   B     400  1:8  100    100   0                                  14  A     100  B     50   2:1  75     100   33                                 15  A     100  B     100  1:1  79     100   26                                 16  A     100  B     200  1:2  88     100   14                                 17  A     100  B     400  1:4  100    100   0                                  18  A     200  B     50   4:1  84     91    8                                  19  A     200  B     100  2:1  87     100   15                                 20  A     200  B     200  1:1  92     100   9                                  21  A     200  B     400  1:2  100    100   0                                  22  A     400  B     50   8:1  100    100   0                                  23  A     400  B     100  4:1  100    100   0                                  24  A     400  B     200  2:1  100    100   0                                  25  A     400  B     400  1:1  100    100   0                                  __________________________________________________________________________      .sup.(1) Test Nos. 1-9 are control runs with Test 1 being a no chemical        control (surfactant/acetone/water/alone).                                      .sup.(2) Chemical A represents O,O--diethyl                                    O--(3,5,6trichloro-2-pyridinyl) phosphorothioate.                              .sup.(3) Chemical B represents N--cyclopropyl                                  O--(2cyclopropyl-5-pyrimidinyl) O--ethyl phosphoramidothioate.                 .sup.(4) Expected control equals % control by chemical A + % control by        chemical B minus (- )                                                          ##STR16##                                                                      ##STR17##                                                                

EXAMPLE VIII

A study was conducted to determine the effectiveness and enhancing response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-n-propyl phosphoramidothioate (Compound 5) in the control of Heliothis larvae.

Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant.

The leaves of 5-6 week old cotton seedlings were dipped into one of the above mixtures and allowed to dry. When dry they were removed from the plant and placed into Petri dishes. Five late second instar (approximately 5-day old) tobacco budworm larvae (Heliothis virescens) were placed in each dish and the dishes covered. All treatments were run in triplicate. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants.

The results of this study are set forth below in Table IV.

                                      TABLE IV                                     __________________________________________________________________________                                    Expected                                                                              Actual                                   Test      Amount     Amount                                                                              Ratio of                                                                            Control                                                                               Control                                                                              Percent Increase Over              No..sup.(1)                                                                        Chemical.sup.(2)                                                                     in PPM                                                                              Chemical.sup.(3)                                                                     in PPM                                                                              A to B                                                                              in Percent.sup.(4)                                                                    in Percent                                                                           Expected Control.sup.(5)           __________________________________________________________________________     1   --    --   --    --   --   --    0      --                                 2   A     50   --    --   --   --    0      --                                 3   A     100  --    --   --   --    33     --                                 4   A     200  --    --   --   --    67     --                                 5   A     400  --    --   --   --    93     --                                 6   --    --   B     50   --   --    0      --                                 7   --    --   B     100  --   --    7      --                                 8   --    --   B     200  --   --    7      --                                 9   --    --   B     400  --   --    40     --                                 10  A     50   B     50   1:1  0     67     >100.sup.(6)                       11  A     50   B     100  1:2  33    73     121                                12  A     50   B     200  1:4  7     100    1328                               13  A     50   B     400  1:8  40    93     132                                14  A     100  B     50   2:1  33    93     182                                15  A     100  B     100  1:1  38    100    163                                16  A     100  B     200  1:2  38    100    163                                17  A     100  B     400  1:4  60    100    67                                 18  A     200  B     50   4:1  67    100    49                                 19  A     200  B     100  2:1  69    100    45                                 20  A     200  B     200  1:1  69    100    45                                 21  A     200  B     400  1:2  80    100    20                                 22  A     400  B     50   8:1  93    100    7                                  23  A     400  B     100  4:1  93    100    7                                  24  A     400  B     200  2:1  93    100    7                                  25  A     400  B     400  1:1  96    100    4                                  __________________________________________________________________________      .sup.(1) Test Nos. 1-9 are control runs with Test 1 being a no chemical        control (surfactant/acetone/water/alone).                                      .sup.(2) Chemical A represents O,O--diethyl                                    O--(3,5,6trichloro-2-pyridinyl) phosphorothioate.                              .sup.(3) Chemical B represents O--(2cyclopropyl-5-pyrimidinyl) O--ethyl        N---phosphoramidothioate.                                                      .sup.(4) Expected control equals % control by chemical A + % control by        chemical B minus (-)                                                           ##STR18##                                                                      ##STR19##                                                                      .sup.(6) Percentage to great to compute.                                 

EXAMPLE IX

A study was conducted to determine the amount in parts of active compound per million parts of the ultimate compositions (ppm) of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate, alone, and in a 1:1 ratio of said compound with one of the compounds set forth in Example V necessary to give at least a 95 percent (LD₉₅) kill and control of Heliothis larvae.

Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant.

The leaves of 5-6 week old cotton seedlings were dipped into one of the above mixtures and allowed to dry. When dry they were removed from the plant and placed into Petri dishes. Five late third instar (approximately 5-day old) tobacco budworm larvae (Heliothis virescens) were placed in each dish and the dishes covered. All treatments were run in triplicate. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants.

The results of this study are set forth below in Table V.

                  TABLE V                                                          ______________________________________                                          ##STR20##                                                                     LD.sub.95 of 1:1 Ratio of O,O--diethyl O--(3,5,6-trichloro-2-pyridinyl)        phosphorothioate with indicated compound from Example V.                       Amount listed under LD.sub.95 is amount of each compound in PPM                present. LD.sub.95 for each compound from Example V alone                      is >200 ppm.                                                                   Compound                                                                               LD.sub.95                                                                              Compound  LD.sub.95                                                                            Compound LD.sub.95                             ______________________________________                                         1       >200    14        >200  27       >200                                  2       200     15        175   28       >200                                  3       125     16        >200  29       125                                   4       80      17        >200  30       100                                   5       90      18        >200  31       90                                    6       >200    19        >200  32       200                                   7       >200    20        200   33       >200                                  8       >200    21        >200  34       >200                                  9       >200    22        >200  35       >200                                  10      80      23        >200  36       >200                                  11      125     24        >200  37       >200                                  12      175     25        200   38       >200                                  13      >200    26        > 200 39       >200                                                                  40       >200                                  ______________________________________                                     

What is claimed is:
 1. An insecticidal composition which comprises an inert carrier and an insecticidally effective amount of an active mixture of toxicants which mixture comprises about 1 part by weight of O,O-diethyl O-(3,5-6-trichloro-2-pyridinyl)phosphorothioate in admixture with from 1/8 part to about 4 parts by weight of a pyrimidinyl phosphoramidothioate selected from the group consisting ofO-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-(1-methylethyl)phosphoramidothioate, O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-n-propyl phosphoramidothioate and N-cyclopropyl O-(2-cyclo-propyl-5-pyrimidinyl) O-ethyl phosphoramidothioate.
 2. A method for killing and controlling insects of the genus Heliothis which comprises contacting said insects or their habitat with an insecticidally effective amount of a composition which comprises an inert carrier in intimate admixture with an active mixture of toxicants which mixture comprises about 1 part by weight of O,O-diethyl O-(3,5-6-trichloro-2-pyridinyl) phosphorothioate in admixture with from 1/8 part to about 4 parts by weight of a pyrimidinyl phosphoramidothioate selected from the group consisting ofO-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-(1-methylethyl)phosphoramidothioate, O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-n-propyl phosphoramidothioate and N-cyclopropyl O-(2-cyclo-propyl-5-pyrimidinyl) O-ethyl phosphoramidothioate.
 3. An insecticidal composition which comprises an inert carrier and an insecticidally effective amount of an active mixture of toxicants which mixture comprises about 1 part by weight of a pyridinyl phosphorus insecticide corresponding to the formula ##STR21## wherein each X independently represents bromo, chloro, fluoro or iodo; Z represents oxygen or sulfur; each R independently represents alkoxy of 1 to 4 carbon atoms, and n represents an integer of from 1 to 3 in admixture with from about 1/16 part to about 16 parts by weight of a pyrimidinyl phosphoramidothioate corresponding to the formula ##STR22## wherein A represents alkyl of 1 to 4 carbon atoms, cycloalkyl of 3 or 4 carbon atoms, alkyl(cycloalkyl) wherein the alkyl group is of 1 to 4 carbon atoms and the cycloalkyl group is of 3 or 4 carbon atoms, (cycloalkyl)alkyl wherein the alkyl group is of 1 to 4 carbon atoms and the cycloalkyl group is of 3 or 4 carbon atoms, dialkylamino wherein each alkyl group is independently of 1 to 4 carbon atoms or morpholino; D represents hydrogen, methyl, alkoxy of 1 to 4 carbon atoms or alkylthio of 1 to 4 carbon atoms; R¹ represents alkyl of 1 to 4 carbon atoms; R² represents monoalkylamino of 1 to 4 carbon atoms, dialkylamino wherein each alkyl group is independently of 1 to 4 carbon atoms or monocycloalkylamino of 3 to 4 carbon atoms and Z is oxygen or sulfur.
 4. The composition as defined in claim 1 wherein the inert carrier is an inert liquid carrier.
 5. The composition as defined in claim 4 wherein the active mixture of toxicants is present in an amount of from about 0.01 to about 95 percent by weight of the total composition.
 6. The composition as defined in claim 5 wherein the composition is present as an aqueous dispersion and the mixture of toxicants is present in an amount of from about 0.1 to about 50 percent by weight of the total composition.
 7. The composition as defined in claim 1 wherein the pyrimidinyl phosphoramidothioate is O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-(1-methylethyl) phosphoramidothioate.
 8. The composition as defined in claim 1 wherein the pyrimidinyl phosphoramidothioate is O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-n-propyl phosphoramidothioate.
 9. The composition as defined in claim 1 wherein the pyrimidinyl phosphoramidothioate is N-cyclopropyl O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl phosphoramidothioate.
 10. The method as defined in claim 2 wherein the composition is employed in amounts of from about 1/16 pound to about 5 pounds per acre.
 11. The method as defined in claim 2 wherein the active pyrimidinyl phosphoramidothioate is O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-(1-methylethyl) phosphoramidothioate.
 12. The method as defined in claim 2 wherein the active pyrimidinyl phosphoramidothioate is O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl N-n-propyl phosphoramidothioate.
 13. The method as defined in claim 2 wherein the active pyrimidinyl phosphoramidothioate is N-cyclopropyl O-(2-cyclopropyl-5-pyrimidinyl) O-ethyl phosphoramidothioate. 